Refactor menu structure and add Flutter-specific input and persistence layers

- Moved menu-related classes to a new structure under `src/menu/`.
- Introduced `WolfMenuPresentation` to handle menu art and mappings.
- Added `MenuManager` tests to ensure menu state reflects game status.
- Implemented `FlutterRendererSettingsPersistence` and `FlutterSaveGamePersistence` for managing settings and save files on desktop platforms.
- Created `Wolf3dFlutterInput` to handle keyboard and mouse input in a Flutter environment.
- Updated README to reflect new package structure and usage instructions.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

packages/wolf_3d_dart/test/menu/menu_manager_test.dart

@@ -0,0 +1,167 @@
+import 'package:test/test.dart';
+import 'package:wolf_3d_dart/src/menu/menu_manager.dart';
+import 'package:wolf_3d_dart/wolf_3d_engine.dart';
+
+void main() {
+  group('MenuManager', () {
+    test('main menu row enablement reflects resumable and loadable state', () {
+      final manager = MenuManager();
+
+      manager.showMainMenu(hasResumableGame: false, hasLoadableSave: false);
+
+      expect(
+        _entryFor(manager, WolfMenuMainAction.loadGame).isEnabled,
+        isFalse,
+      );
+      expect(
+        _entryFor(manager, WolfMenuMainAction.saveGame).isEnabled,
+        isFalse,
+      );
+      expect(
+        _entryFor(manager, WolfMenuMainAction.changeView).isEnabled,
+        isTrue,
+      );
+
+      manager.setLoadGameAvailable(true);
+
+      expect(_entryFor(manager, WolfMenuMainAction.loadGame).isEnabled, isTrue);
+      expect(
+        _entryFor(manager, WolfMenuMainAction.saveGame).isEnabled,
+        isFalse,
+      );
+
+      manager.showMainMenu(hasResumableGame: true, hasLoadableSave: true);
+
+      expect(_entryFor(manager, WolfMenuMainAction.saveGame).isEnabled, isTrue);
+      expect(_entryFor(manager, WolfMenuMainAction.endGame).isEnabled, isTrue);
+      expect(
+        manager.mainMenuEntries.any(
+          (entry) => entry.action == WolfMenuMainAction.backToGame,
+        ),
+        isTrue,
+      );
+    });
+
+    test('change-view navigation skips disabled renderer rows and options', () {
+      final manager = MenuManager();
+
+      manager.setChangeViewEntries(const <WolfMenuRendererEntry>[
+        WolfMenuRendererEntry(
+          mode: WolfRendererMode.software,
+          label: 'SOFTWARE',
+          hasOptions: false,
+          isEnabled: false,
+        ),
+        WolfMenuRendererEntry(
+          mode: WolfRendererMode.ascii,
+          label: 'ASCII',
+          hasOptions: true,
+        ),
+      ]);
+      manager.setRendererOptionEntries(
+        title: 'ASCII OPTIONS',
+        entries: const <WolfMenuRendererOptionEntry>[
+          WolfMenuRendererOptionEntry(
+            id: WolfRendererOptionId.asciiTheme,
+            label: 'THEME',
+            isEnabled: false,
+          ),
+          WolfMenuRendererOptionEntry(
+            id: WolfRendererOptionId.fpsCounter,
+            label: 'FPS',
+          ),
+        ],
+      );
+
+      manager.showChangeViewMenu();
+
+      expect(manager.selectedChangeViewIndex, 1);
+
+      manager.updateChangeViewMenu(const EngineInput(isMovingBackward: true));
+      manager.updateChangeViewMenu(const EngineInput());
+
+      expect(manager.selectedChangeViewIndex, 3);
+    });
+
+    test(
+      'renderer option selection is preserved by option id when entries refresh',
+      () {
+        final manager = MenuManager();
+
+        manager.setChangeViewEntries(const <WolfMenuRendererEntry>[
+          WolfMenuRendererEntry(
+            mode: WolfRendererMode.ascii,
+            label: 'ASCII',
+            hasOptions: true,
+          ),
+        ]);
+        manager.setRendererOptionEntries(
+          title: 'ASCII OPTIONS',
+          entries: const <WolfMenuRendererOptionEntry>[
+            WolfMenuRendererOptionEntry(
+              id: WolfRendererOptionId.asciiTheme,
+              label: 'THEME',
+            ),
+            WolfMenuRendererOptionEntry(
+              id: WolfRendererOptionId.fpsCounter,
+              label: 'FPS',
+            ),
+          ],
+        );
+
+        manager.showRendererOptionsMenu();
+        manager.updateRendererOptionsMenu(
+          const EngineInput(isMovingBackward: true),
+        );
+        manager.updateRendererOptionsMenu(const EngineInput());
+
+        expect(manager.selectedRendererOptionIndex, 1);
+
+        manager.setRendererOptionEntries(
+          title: 'ASCII OPTIONS',
+          entries: const <WolfMenuRendererOptionEntry>[
+            WolfMenuRendererOptionEntry(
+              id: WolfRendererOptionId.fpsCounter,
+              label: 'FPS',
+            ),
+            WolfMenuRendererOptionEntry(
+              id: WolfRendererOptionId.asciiTheme,
+              label: 'THEME',
+            ),
+          ],
+        );
+
+        expect(manager.selectedRendererOptionIndex, 0);
+        expect(
+          manager.rendererOptionEntries[manager.selectedRendererOptionIndex].id,
+          WolfRendererOptionId.fpsCounter,
+        );
+      },
+    );
+
+    test('transition locks navigation and reports none when idle', () {
+      final manager = MenuManager();
+
+      manager.showMainMenu(hasResumableGame: false);
+      manager.startTransition(WolfMenuScreen.difficultySelect);
+
+      final result = manager.updateMainMenu(
+        const EngineInput(isMovingBackward: true, isInteracting: true),
+      );
+
+      expect(result.selected, isNull);
+      expect(result.goBack, isFalse);
+      expect(manager.transitionEffect, WolfTransitionEffect.normalFade);
+
+      manager.tickTransition(MenuManager.transitionDurationMs);
+
+      expect(manager.isTransitioning, isFalse);
+      expect(manager.transitionEffect, WolfTransitionEffect.none);
+      expect(manager.activeMenu, WolfMenuScreen.difficultySelect);
+    });
+  });
+}
+
+WolfMenuMainEntry _entryFor(MenuManager manager, WolfMenuMainAction action) {
+  return manager.mainMenuEntries.firstWhere((entry) => entry.action == action);
+}

packages/wolf_3d_dart/test/registry/spear_demo_registry_test.dart

@@ -1,4 +1,5 @@
 import 'package:test/test.dart';
+import 'package:wolf_3d_dart/src/registry/built_in/spear_menu_presentation_module.dart';
 import 'package:wolf_3d_dart/wolf_3d_data_types.dart';
 import 'package:wolf_3d_dart/wolf_3d_entities.dart';
 
@@ -17,6 +18,7 @@ void main() {
       expect(registry.hud.resolve(HudKey.statusBar)?.vgaIndex, 73);
       expect(registry.hud.resolve(HudKey.digit0)?.vgaIndex, 84);
       expect(registry.hud.resolve(HudKey.pistolIcon)?.vgaIndex, 77);
+      expect(registry.menuPresentation, isA<SpearMenuPresentationModule>());
     });
 
     test('resolves SDM enemy sprite ranges with +4 SPEAR shift', () {

packages/wolf_3d_dart/test/registry/wolf_classic_menu_art_mapping_test.dart

@@ -21,14 +21,14 @@ void main() {
         vgaImages: List.generate(120, (i) => _img(height: i + 1)),
       );
 
-      final art = WolfClassicMenuArt(data);
+      final menu = WolfMenuPresentation(data);
 
       // Retail cursor constants 8/9 must resolve to shareware cursor IDs 20/21.
-      expect(art.mappedPic(8)?.height, 21);
-      expect(art.mappedPic(9)?.height, 22);
+      expect(menu.mappedPic(8)?.height, 21);
+      expect(menu.mappedPic(9)?.height, 22);
 
       // Retail footer constant 15 must resolve to shareware footer ID 27.
-      expect(art.mappedPic(15)?.height, 28);
+      expect(menu.mappedPic(15)?.height, 28);
     },
   );
 }